Liolaemus nigrodorsum, Troncoso-Palacios & Contreras-Piderit, 2023

Troncoso-Palacios, Jaime & Contreras-Piderit, Francisco, 2023, A new species of the Liolaemus nigroviridis group from the Andes of Central Chile (Iguania: Liolaemidae), Acta Zoológica Lilloana 67 (1), pp. 233-259 : 245-253

Liolaemus nigrodorsum sp. nov. Fig. 4

2005 Liolaemus nigroviridis, Torres-Pérez, Gómez-Lobo, Garín. Herpetological Review 36, p. 80.

2013 Liolaemus nigroviridis, Garín and Hussein. Guía de Reconocimiento de Anfibios y Reptiles , p. 48.

2013 Liolaemus nigroviridis, Cianferoni, Yáñez, Palma, Garín, Torres-Pérez. Zootaxa 3619, p. 60.

2016 Liolaemus nigroviridis (?), Troncoso-Palacios, Elorza, Puas, Alfaro-Pardo. Zookeys 555, p. 91.

2017 Liolaemus nigroviridis (in map), Torres-Pérez, Boric-Bargetto, Rodríguez-Valenzuela, Escobar, Palma. Revista Chilena de Historia Natural 90, p. 3.

Holotype.— SSUC Re 787. Adult male ( Fig. 4A, B ). Collected in the ski center El Arpa (32º39’31’’S – 70º28’46’’W, 2604 m above sea level), approximately 21 km NE Los Andes city, Valparaíso Region, Chile. Collectors: J. Troncoso-Palacios and F. Contreras. January 11, 2021.

Paratypes ( Fig. 4C, D, E, F ).— SSUC Re 788–90, three males. SSUC Re 791–93, three females. SSUC Re 794, juvenile. Same data as the holotype. SSUC Re 005–06. Two males. SSUC Re 001–04. Four juveniles. Ski center El Arpa (32°39’S – 70°28’W) Collectors: F. Torres-Pérez and G. Lobos. September 10, 2003 .

Etymology.— The name of this species is a composition of “ nigro ”, from the Latin word “ niger ” (black) and the Latin word “ dorsum ” (back). The species epithet made reference to the color pattern of the males.

Diagnosis.— DNA phylogenetic evidence shows that Liolaemus nigrodorsum sp. nov. is a member of the L. nigroviridis group ( Cianferoni et al., 2013; Torres-Pérez et al., 2017), being the sister species of L. nigroviridis ( Fig. 1 , Table 3). It shows the morphological features of this group ( Pincheira-Donoso and Núñez, 2005; Troncoso-Palacios et al., 2016), which are robust lizards with black dorsal stripes and yellow dorsal scales, males have precloacal pores and are bigger than females. Almost all species have approximately 54–64 scales around midbody.

Liolaemus nigrodorsum sp. nov. strongly differs from L. campanae in color pattern, especially among males ( Fig. 5 ). The males of L. campanae have orange or yellow background color on the occipital band (wide and extended between the lateral fields) and light green on the lateral fields, with thin black stripes forming a reticulation; whereas the males of L. nigrodorsum sp. nov. have yellow or white background color on the occipital band (wide and extended between the lateral fields) and yellow on the lateral fields (light green color is absent or is inconspicuous, restricted to the sides of the neck and the dorsal base of the tail), with thick black stripes forming a reticulation or almost complete melanism on the occipital band area. Females of L. campanae have brown background color between the dorsolateral bands with reddish shades on the dorsolateral bands and the lateral fields in several individuals, whereas the females of L. nigrodorsum sp. nov. completely lack the reddish color.

Liolaemus nigrodorsum sp. nov. is bigger than L. fuscus (maximum SVL = 78.8 mm vs 52.3 mm, Tables 2 and 4), has more midbody scales (60.3 ± 2.9 vs 45.4 ± 2.5, Table 2, 4) and more dorsal scales (54.8 ± 1.1 vs 35.6 ± 3.9, Tables 2 and 4). Moreover, L. fuscus lack sexual dichromatism and although its dorsal color pattern loosely resembles the color pattern in the juveniles and females of L. nigrodorsum sp. nov., the males never have black thick dorsal reticulation or partial melanism as the males of L. nigrodorsum sp. nov. ( Fig. 5 ). We remark that L. nigrodorsum sp. nov. and L. fuscus do not overlap in the PC1 vs PC2 and PC2 vs PC3 graphs, in both, the PCA with the snout-vent length and the PCA with the residuals of each character regressed on snout-vent length ( Figs. 2 and 3 ), explained by the small size and the slender body shape of L. fuscus .

Liolaemus nigrodorsum sp. nov. has more supralabial scales than L. nigroviridis (7 vs 5.8 ± 0.6, Table 2, 4). The dorsal color pattern of the males of L. nigroviridis is more variable than in the other species analyzed, but never has a pattern similar to Liolaemus nigrodorsum sp. nov. ( Fig. 5 ). In fact, L. nigroviridis males have the following color combinations of background color on the occipital band (wide and extend- ed between the lateral fields) and the lateral fields, respectively: light green-light green, light green-yellow and yellow-yellow, always with thin black stripes forming a reticulation, whereas the males of L. nigrodorsum sp. nov. have only yellow-yellow or white-yellow color combinations, with thick black stripes forming a reticulation or almost complete dorsal melanism and the light green color is absent or is inconspicuous (restricted to the sides of the neck and/or on the dorsal base of the tail). We point out that L. nigrodorsum sp. nov. and L. nigroviridis overlap, but always with different orientation axis, in the PCAs graphs constructed with the residuals of each character regressed on snout-vent length ( Fig. 2 ). Remarkably, both species do not overlap in in the PCAs graphs constructed with the snout-vent length ( Fig. 3 ), probably explained by the bigger size of L. nigrodorsum sp. nov. (maximum SVL = 78.8 mm vs 73.8 mm, Table 4).

Liolaemus nigrodorsum sp. nov. is smaller than L. uniformis (SVL = 78.8 mm vs 89.1 mm, Tables 2 and 4). Both species are easily distinguishable, because L. uniformis lacks sexual dichromatism and has no noticeable dorsal color pattern ( Fig. 5 ). In fact, it has brown dorsal color, with few whitish or dark scales dispersed, whereas L. nigrodorsum sp. nov. has marked sexual dichromatism and males and females have dorsal pattern with think black stripes forming a reticulation or partial melanism on males, and dorsolateral dark bands with fragmented vertebral line in females.

A summary of these features is provided in Table 4.

Description of holotype.— Adult male. SVL = 76.2 mm. Horizontal diameter of the eye: 3.5 mm. Subocular length: 4.2 mm. Length of the fourth supralabial: 3.4 mm. Head length (from the anterior border of the auditory meatus to the tip of the snout): 16.5 mm. Head height (at the level of ear openings): 8.9 mm. Head width (distance between the two ear openings): 14.3 mm. Neck width: 15.1 mm. Interorbital distance: 5.4 mm. Ear-eye distance: 6.8 mm. Internasal scales distance: 2.4 mm. Ear width: 1.7 mm. Ear height: 3.0 mm. Axilla-groin distance: 35.0 mm. Body width: 21.7 mm. Forelimb length: 24.2 mm. Hindlimb length: 42.4 mm. Tail length (not autotomized): 126.0 mm, relation tail length/SVL = 1.7. Rostral scale, wider (3.1 mm) than high (1.4 mm).

Two postrostrals. Four internasals. The Interparietal is hexagonal, with a small central spot marking the position of the parietal eye. The interparietal is smaller than the parietals and is surrounded by ten scales. The parietal scales are in contact. Seven scales between the interparietal and rostral. Thirteen scales between the occiput and the rostral. Orbital semicircles are complete and formed by 11 (left) and 12 (right) scales. Four supraoculars on both sides. Seven superciliary scales. The frontal area is divided into three scales, from anterior to posterior: 1 and 2. Preocular separated from the lorilabials by one loreal scale. Two scales between nasal and canthal. The nasal is in contact with the rostral and surrounded by seven scales (including the rostral). One row of lorilabials is between the supralabials and the subocular. Seven supralabials, the fourth is curved upward without contacting the subocular. Six infralabials scales. The Pentagonal mental scale, in contact with four scales. Four pairs of post-mental shields, the second is separated by two scales. The temporal scales are of variable shape, but mainly hexagonal, slightly keeled or smooth, juxtaposed or subimbricated. Eight temporal scales are between the level of superciliary scales and the rictal level. There are five projected scales on the anterior edge of the ear, which do not cover the auditory meatus. Differentiated auricular scale, wide, placed on the upper section of the auditory meatus. There are thirty-four gular scales between the auditory meatuses. The lateral neck fold is “Y” shaped. There is an antehumeral transversal neck fold. There is a slightly developed dorso-lateral fold running from the neck to the half the groin. Midbody scales: 64. Dorsal scales are lanceolate, imbricate and keeled with mucron, almost without interstitial granules. Dorsal scales and ventral scales have similar size. Dorsal scales: 54. Ventral scales are rounded, smooth, imbricated and without interstitial granules. Ventral scales: 101. Two dark brown precloacal pores. Supra-femoral scales are lanceolate, imbricate and keeled, some have a mucron. Infra-femoral scales are rounded, smooth and imbricated. Supra-antebrachial scales are lanceolate, imbricate and keeled, some have a mucron. The Infra-antebrachials are rounded or rhomboidal, imbricated and smooth or slightly keeled, imbricated or juxtaposed, with interstitial granules. Dorsal scales of the first third of the tail are rhomboidal, imbricate, keeled and mucronate. Ventral scales: in the first third of the tail are rounded, smooth and imbricate. Lamellae of the fingers: I: 8, II: 13, III: 17, IV: 19 and V: 11. Lamellae of the toes: I: 10, II: 15, III: 19, IV: 25 and V: 16.

Color of holotype in life.— The dorsal pattern is as follows: Dorsal field of the head and temporal area are black, with abundant white and light brown dispersed dots. Wide occipital band (there are no other discernible bands between the lateral fields), covering both, dorsal and dorsolateral fields, running from the neck to the base of the tail. It is black, with several yellow dots on the dorsum forming inconspicuous fragmented transversal lines. The subocular field of the head and the sides of the neck are whitish with thick black lines that from a reticulation. The lateral fields are yellow with ten transversal black thick stripes, between the axilla and the groin, some of these are partially fused. “H” shaped black spot over the shoulder, on the pre and post scapular area. The ventral field (side view) is whitish, with the same transversal black thick stripes of the lateral field running through it. The Forelimbs and hind limbs are light yellow with transversal black thick stripes. The tail is light brown, with yellowish shades. There are few black dots on the vertebral zone, without forming an inconspicuous fragmented vertebral line. Ventrally, the gular area and the chest are whitish with black transversal thick stripes, forming a reticulation. The sides of the abdominal area are whitish with transversal thick black stripes. The middle of the abdominal area and the area between the groins and the cloaca are whitish with transversal thin black fragmented stripes and a ventral black line running from the chest to the cloaca. There are yellowish shades on the chest and cloacal area. Ventrally, the limbs are white with black stripes, but the palms are white. The base of the tail is white with a few black dots, but the rest of the tail is white.

Variation.— Based on six adult males: SVL: 65.1–78.8 mm (73.2 ± 4.6). Axilla-groin distance: 26.4–35.2 mm (31.5 ± 3.3). Head length: 15.3–17.8 mm (16.4 ± 0.8). Head width: 12.2–14.9 mm (13.7 ± 1.0). Head height: 7.4–13.2 mm (9.8 ± 2.0). Leg length: 38.5–42.4 mm (40.0 ± 1.7). Arm length: 21.9–24.3 mm (23.4 ± 0.9). Foot length: 20.3–22.0 mm (21.4 ± 0.6). Tail length: 126.0 mm (only one specimen, autotomized in the rest). Tail length/SVL = 1.7 (n = 1). In three adult females: SVL: 59.1–62.5 mm (61.1 ± 1.8). Axilla-groin distance: 24.7–28.4 mm (27.1 ± 2.0). Head length: 12.4–12.9 mm (12.8 ± 0.3). Head width: 10.3–10.8 mm (10.6 ± 0.3). Head height: 6.1–7.6 mm (7.0 ± 0.8). Leg length: 29.8–30.9 mm (30.3 ± 0.6). Arm length: 18.4–19.7 mm (19.3 ± 0.8). Foot length: 16.7–17.0 mm (17.0 ± 0.2). Tail length: 91.0–111.0 mm (101.0 ± 14.1, two specimens, autotomized on another), with relation tail length/SVL = 1.5–1.9 (1.7 ± 0.3, n = 2).

The variation in the scalation on the male adult specimens is as follows. Midbody scales: 56–64 (60.3 ± 2.9). Dorsal scales: 54–57 (54.8 ± 1.1). Ventral scales: 86–101 (92.1 ± 5.9). Fourth finger lamellae: 18–20 (19.2 ± 0.9). Fourth toe lamellae: 24–29 (26.5 ± 1.8). Supralabial scales: 7, the fourth curved upward. Infralabial scales: 5–6 (5.5 ± 0.5). The variation in the scalation on the female adult specimens is as follows. Midbody scales: 54–60 (57.3 ± 3.1). Dorsal scales: 52–59 (55.3 ± 3.5). Ventral scales: 97–109 (102.7 ± 6.0). Fourth finger lamellae: 19–20 (19.3 ± 0.6). Fourth toe lamellae: 24–28 (26.7 ± 2.3). Supralabial scales: 6, the fourth curved upward. Infralabial scales: 5. On the adult specimens of both sexes, the interparietal scale is pentagonal, hexagonal or heptagonal bordered by 6–10 scales (7.5 ± 2.0). Interparietals are smaller than the parietal scales or have similar size. Interparietals are in contact or separated. Nasal and rostral are in contact or separated by one scale. Precloacal pores in males: 2–3 (2.1 ± 0.4). Precloacal pores are absent in females.

Adult male paratypes have a similar color pattern compared with the holotype. Some males have white dots between the lateral fields (on the black area formed by the wide occipital band), forming fragmented transversal stripes instead of yellow dorsal dots between the lateral fields, forming fragmented transversal stripes as on the holotype. Some males have thick black reticulation and yellow or whitish background color between the lateral fields (on the black area formed by the wide occipital band) instead of black dorsal color as on the holotype. There are males with an inconspicuous light green shade restricted to the sides of the neck and/or on the dorsal base of the tail. The black transversal stripes on the lateral fields are continued on the ventrolateral fields and vary from nine to 11. Male juveniles have dark brown dorsal color between the lateral fields, instead of black dorsal color as in the adult male holotype, and have a dark brown fragmented vertebral line running from the occiput to almost the tip of the tail. In the adult females the dorsal surface of the head is light brown with some dispersed dark brown spots. The temporal area and the sides on the neck are brown with few light yellow or white fragmented transversal stripes. There is a dark brown fragmented vertebral line running from the occiput to almost the tip of the tail and some white dots dispersed on the vertebral field. There are approximately 10 series of paravertebral spots composed of a dark brown anterior area and white posterior area (few and inconspicuous in some females). The lateral field is yellow or white with light brown or dark brown transversal stripes which continue to the whitish ventrolateral filed. The dorsal surface of the limbs is brown with few and inconspicuous light or dark brown sports dispersed. The dorsal surface of the tail is light brown with a dark brown fragmented vertebral line accompanied by dark brown dots (almost immaculate tail in some females). Ventrally, the gular area is white with black reticulation. The chest is white with dark spots dispersed. The belly and the tail are white. The sides of the belly have yellow in almost all females. The ventral surface of the limbs is white with dark brown dots dispersed.

Distribution and natural history.— This species is currently known only from the type locality in El Arpa ski center, approximately 21 km NE of Los Andes, Valparaíso Region, Chile ( Fig. 6 ). It was found between 2604 (32º39’31’’S – 70º28’46’’W) and 3059 masl (32º39’24’’S – 70º28’01’’W) inhabiting rocky areas with shrubby vegetation composed mainly of high-Andean bushes such as Tetraglochin alatum , Mulinum spinosum and Chuquiraga oppositifolia . This lizard species was found in abundance and was observed to have saxicolous habits. We found individuals in syntopy with Liolaemus monticola Müller and Hellmich 1932 , whereas L. nitidus (Wiegmann, 1834) was found near at lower altitudes. Besides, Troncoso-Palacios et al. (2016), based on field observations, recorded “ L. nigroviridis ” from the surroundings of the Chepical Lagoon, Valparaíso Region, Chile (32º16’S – 70º30’W). Although no specimens were collected, most likely, this record is assignable to L. nigrodorsum sp. nov. since the color pattern matches this species (JTP, personal observations).

Several males were observed near a female (less than five meters). While the reproductive mode is yet unknown, at the time of sampling (January) no evidence of embryos was found, all females have several small oocytes.

Figures

Figure 1. Phylogenetic relationships of the species of the L. nigroviridis complex group, modified from Torres-Pérez et al. (2017), based on the mitochondrial gene cytochrome b, including the bootstrap values for maximum likelihood, the posterior probabilities for Bayesian inference and the number of haplotypes used for each terminal taxon. Liolaemus fuscus is added as the basal species of the group, following Schulte and Moreno-Roark (2010), Troncoso-Palacios et al. (2015) and Esquerré et al. (2022). Specific name L. nigroviridis is used only for the clade that contains the samples from near the type locality. The candidate species Liolaemus sp. Arpa is in red. Male dorsal pattern is compared.

Figure 2. Principal Component Analysis (PCA) plots of the species of the L. nigroviridis group, performed with the residuals of each character regressed on snout-vent length. On the left panels, the individuals are colored according to their species as shown on the legend on the top right corner. Ellipses represent the 95% confidence interval around the centroid for each species. On each axis, the PC is labeled according to its number and the percentage of the total variance that PC explains. On the right, the variable graphs, which illustrate the contribution of each variable to the construction of the axes.

Figure 3. Principal Component Analysis (PCA) plots of the species of the L. nigroviridis group, performed with the snout-vent length as a variable. On the left panels, the individuals are colored according to their species as shown on the legend on the top left corner. Ellipses represent the 95% confidence interval around the centroid for each species. On each axis, the PC is labeled according to its number and the percentage of the total variance that PC explains. On the right, the variable graphs, which illustrate the contribution of each variable to the construction of the axes.

Figure 4. Liolaemus nigrodorsum sp. nov. A) and B) Holotype, male SSUC Re 787. C) and D) Paratype, female SSUC Re 792. E) SSUC Re 789 and F) SSUC Re 788, paratypes, males.

Figure 5. Species of the Liolaemus nigroviridis group. A) Male of L. campanae (photograph by S. Berhó Fuenzalida). B) Female of L. campanae (photograph by R. Arroyo Castro). C) and D) Males of L. fuscus (photographs by JTP). E) and F) Males of L. nigroviridis (photographs by JTP). G) Female of L. nigroviridis (photograph by JTP). H) and I) Male and female, respectively, of of L. uniformis (photographs by JTP).

Figure 6. Distributional map for Liolaemus nigrodorsum sp. nov. along with the species of the L. nigroviridis group following the most recent phylogenetic studies (Torres–Pérez et al., 2017; Esquerré et al., 2022). Liolaemus campanae: Blue circles (1 = La Campana, 2 = El Roble, 3 = Chicauma). Liolaemus fuscus: Black circles (1 = Los Molles, 2 = Altos de Jahuel, 3 = La Campana, 4 = El Roble, 5 = Cerro Blanco, 6 = Chicauma, 7 = Farellones, 8 = Quebra de la Plata, 9 = Quebrade de Macul, 10 = San Luis de Macul). Liolaemus nigrodorsum sp. nov: Red circle (El Arpa, type locality) and question mark (Laguna Chepical, possible record). Liolaemus nigroviridis: Green circles (1 = Cerro Conchali, 2 = Farellones, 3 = Lagunillas, 4 = El Yeso). Liolaemus uniformis: pink circle (Laguna Chepical). Liolaemus sp. Cantillana: Yellow circle (Altos de Cantillana).